The principle of the scroll compressor has been known. The scroll compressor is a kind of a positive displacement type compressor in which a pair or scrolls are combined with each other to effect compression of a fluid.
In the ordinary scroll compressor, one of the scrolls is made stationary and the other is subject to an orbital movement with respect to the stationary scroll to effect the compression.
The principle of the total system rotation type scroll compressor in which both scrolls are respectively rotated around their own axial center, is also well known.
FIG. 6 shows the principle of the total system rotation type scroll compressor. A driving scroll 1 is caused to rotate around its own axial center 0.sub.1 by a driving source such as a motor, an engine, a turbine and so on. A driven scroll 2 is also caused to rotate around its axial center 0.sub.2 in synchronism with the rotation of the driving scroll 1. A compression chamber 3, which is formed by combining the driving and driven scrolls 1, 2, moves toward the rotation centers as the both scrolls rotate while the volume of the chamber 3 is gradually reduced. The pressure of a gas confined in the compression chamber 3 increases and a highly pressurized gas is discharged through a discharge port 2c.
FIG. 6a shows a state of the combined driving and driven scrolls 1, 2 at its moving phase of 0.degree., in which the gas is sucked in the compression chamber 3. As the scrolls rotate, they assume the moving phases of 90.degree., 180.degree. and 270.degree. successively, whereby the compression chamber 3 gradually shifts toward their revolution centers with the result of reduction in the volume of the gas. The two scrolls 1, 2 provide sealing portions by mutual contact of the side walls of the wrap plates 1a, 2a of the scrolls 1, 2. As shown in FIG. 6, the sealing portions 5 are in alignment with each other in the radial direction of the driving and driven scrolls 1, 2; namely, they always occupy a constant positional relation in a static state of the scrolls.
U.S. Pat. No. 3,884,599 schematically shows the conventional total system rotation type scroll compressor in FIG. 38. In the construction disclosed in the U.S. Patent, an Oldham's coupling is used to maintain a given phase between a driving scroll and a driven scroll.
In the conventional scroll compressor, there is no control means which controls gaps between the wrap plates of the scroll members. Accordingly, when a gap is produced between the wrap plates during the use of the scroll compressor, the gaps inviting reduction in efficiency of the compressor, it has no way to adjust the gaps.